The sea has long been a source of Norway’s riches, whether from
cod, farmed salmon or oil. Now one researcher hopes to add seaweed to this
list as he refines a way to produce “biocrude” from common
kelp.
Kelp can be turned into a kind of "bio-crude" that can be further
refined into a biofuel. Credit: Rune Petter Ness, NTNU Communication Division
“What we are trying to do is to mimic natural processes to produce
oil,” said Khanh-Quang Tran, an associate professor in Norwegian
University of Science and Technology's (NTNU) Department of Energy and
Process Engineering. “However, while petroleum oil is produced naturally
on a geologic time scale, we can do it in minutes.”
Tran conducted preliminary studies using sugar kelp (Laminaria saccharina),
which grows naturally along the Norwegian coast. His results have just
been published in the academic journal Algal Research.
Learn about more kelp biofuel initiatives here.
The Breakthrough
Using small quartz tube “reactors” — which look like
tiny sealed straws — Tran heated the reactor containing a slurry
made from the kelp biomass and water to 350 degrees C at a very high rate
of 585 degrees C per minute.
The technique, called fast hydrothermal liquefaction, gave him a bio-oil
yield of 79 percent. That means that 79 percent of the kelp biomass in
the reactors was converted to bio-oil. A similar study in the U.K. using
the same species of kelp yielded just 19 percent. The secret, Tran said,
is the rapid heating.
Falling Short on Biofuel Production
Biofuel has long been seen as a promising way to help shift humankind
towards a more sustainable and climate friendly lifestyle. The logic is
simple: petroleum-like fuels made from crops or substances take up CO2
as they grow and release that same CO2 when they are burned, so they are
essentially carbon-neutral.
In its report “Tracking Clean Energy Progress 2014,” the International
Energy Agency (IEA) says that biofuel production worldwide was 113 billion
litres in 2013, and could reach 140 billion litres by 2018.
That may sound like a lot — but the IEA says biofuel production
will need to grow 22-fold by 2025 to produce the amount of biofuel the
world will need to keep global temperatures from rising more than 2oC.
The problem is the biomass feedstock. It’s relatively easy to turn
corn or sugar beets into ethanol that we can pump right into our petrol
tanks. But using food biomass for fuel is more and more problematic as
the world’s population climbs towards 8 billion and beyond.
To get around this problem, biofuel is now produced from non-food biomass
including agricultural residues, land-based energy crops such as fast-growing
trees and grasses, and aquatic crops such as seaweed and microalgae.
All of these feedstocks have their challenges, especially those that are
land based. At least part of the issue is the fact that crops for biofuel
could potentially displace crops for food.
However, seaweed offers all of the advantages of a biofuel feedstock with
the additional benefit of growing, not surprisingly, in the sea.
Scaling Up
But turning big pieces of slippery, salty kelp into biocrude is a challenge,
too. Some studies have used catalysts, which are added chemicals that can
help make the process go more quickly or easily. However, catalysts are
normally expensive and require catalyst recovery.
The UK study that resulted in a 19 percent yield used a catalyst in its
process.
Tran says the advantage of his process is that it is relatively simple
and does not need a catalyst. The high heating rate also results in a biocrude
that has molecular properties that will make it easier to refine.
But Tran’s experiments were what are called screening tests. He
worked with batch reactors that were small and not suitable for an industrial
scale. “When you want to scale up the process you have to work with
a flow reactor,” or a reactor with a continuous flow of reactants
and products, he said. “I already have a very good idea for such
a reactor.”
The Outlook
Even though the preliminary tests gave a yield of 79 percent, Tran believes
he can improve the results even more. He’s now looking for industrial
partners and additional funding to continue his research.
Read the orginal article: http://www.renewableenergyworld.com/rea/news/article/2014/10/turning-humble-seaweed-to-biofuel?cmpid=WNL-Friday-October24-2014
